1. Field
This application is generally related to network routing.
2. Related Art
A communication network may, for example, provide a network connection that allows data to be transferred between two geographically remote locations. A network connection may span multiple links connecting communication devices such as routers. Networks may have different topologies depending on how the links are interconnected through communication devices. Given a particular network topology, multiple routes may be available between a source and destination. Some routes may be more desirable than others depending on current capacity and usage.
Traditional routing algorithms rely on local information each router has from its neighboring links and devices to route data. A router maintains such information in a routing table. The routing table has entries designating a next hop for various destination addresses, or groups of destination addresses. Based on the destination address of an incoming packet, a router uses its routing table to forward the packet to a specific neighboring device. To develop the routing table, each router uses a protocol like Border Gateway Protocol (BGP) to exchange routing and reachability information with local neighboring routers. In this way, each router both forwards packets and conducts control functions to update its own routing table.
While using local information may be desirable in some contexts, it may not always route data efficiently. To route data more efficiently, another technique, referred to as Software Defined Networks (SDNs), separates the control and forwarding functions into separate devices. The control device uses a global knowledge of the network topology to determine a path through the network of forwarding devices for individual data flows. In this way, the routing control device may, for example, establish paths that minimize delay or maximize bandwidth through the network.